Speedometer not moving/working, is the replacement transmission the cause?

I just had my transmission replaced with one I got at a junk yard, the new transmission is working fine, but after everything worked fine yesterday I drove the car today and after 5 minutes of driving the speedometer started jumping everywhere then just dropped down to zero. The car still moves and speeds up normally only the speedometer doesn't work. Did this happen because of the "new" transmission, could it be that a cable/wire wasn't put in right, or could it be something else?